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Title: Matrices
Description: Matrices 12th CET notes

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Matrices
*

*

The matrix A is shortly written as A   a ij 
and the matrix B is shortly written as B   bij 

23

32

Matrices are used in Engineering,
Economics, Statistics, Chemistry, Physics etc
...

The following are row matrices

511 ,  2

7 12 ,

0

3

913

The order of any row matrix is 1  n
...


GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

*

Difference between Matrix and Determinant :
i) A matrix can not have a definite value but
determinant have a definite value
...

iii) Elements of matrix are enclosed in brackets
Discovery :
A British mathematician Arthur Cayley,
formulated the general theory of “Matrices” in
1857
...

If a matrix contains m rows and n columns, we
say that it is an m × n (read m by n) matrix and
m × n is called the order of the matrix
...
The numbers which form a
matrix are called as Elements of matrix
...
g
...


 4
3 
 711 , 2 , 0 
  2 x1  
7  3 x 1
The order of any column matrix is m  1
...

The following are Rectangular Matrices
3 
1 2 3
 2  , 3 2 1 , 1 2 31 3
  2 1 
1  3

The following are column matrices

MHT – CET / JEE (Main)

[1]

3)

4)

Square Matrix :
If number of rows of a matrix are equal to
number of its columns (m = n), then the matrix
is called a Square Matrix
...
In square matrix A= [aij],
diagonal formed by aij, i = j is called as
Principle Diagonal
...
g
...

Diagonal Matrix :
A square matrix whose all non–diagonal
elements are zero is called a Diagonal Matrix
...
e
...

3 0 0 
e
...
0 5 0 
0 0 1 3  3
Number of zeros in a diagonal matrix is given
by n2 – n, where n is order of the matrix
...
i
...

if i) aij = a for i = j,

Matrices

ii) aij = 0 for i ≠ j
...
…L)’ = L’……
...
g
...
It is
also called a Null Matrix
...

i
...
if aij = 0, for i > j
 3 1 5 
1 2 
e
...
0 2 1  , 
0 1 22

0 0 4 3  3

b) Lower Triangular Matrix :
A square matrix whose every element above the
diagonal is zero, is called as Lower Triangular
Matrix
...
e
...

 4 0 0
 1 0
,
e
...
 3 1 0
2 3 22

 6 2 5 3  3
Note: Minimum number of zeros in a triangular
n2  n
matrix is given by
, where n is order of
2
matrix
...
It is denoted by A’
or A t
...

i
...
if i) aij = 1, for i = j,
ii) aij = 0 for i ≠ j
I1 = [1] is the identity matrix of order 1
...

0 1

* (KA)’ = KA’

[2]

* (A’)’ = A

* AT  A

11) Symmetric Matrix :
If the square matrix & its transpose are same
then it is called as Symmetric Matrix
...
e
...
i
...
aij = aji , i ≠ j
...
g
...

 1 2 
12) Skew Symmetric Matrix :
A square matrix A is said to be Skew Symmetric
if A '   A
...

i
...
if i) aij = –aji , i ≠ j &
ii) aij = 0, i = j
...
g
...

ii) A – A’ is a skew symmetric matrix
...

ii) If A and B are symmetric matrices of the same
order then
i) A + B is a symmetric matrix
...

iii) AB – BA is a skew symmetric matrix
...

A  A' A  A'
i
...
A 

2
2
Where

A  A'
A  A'
is symmetric and
is
2
2

skew symmetric matrix
...


Matrices

e
...


Let

Addition or subtraction of two matrices is
nothing but addition or subtraction of their
corresponding elements
...


*
*

If A = diag  d1,d 2 ,d3 ,
...
, 
dn 
 d1 d 2 d 3





Also, A m  diag d1m ,d 2 m ,d 3m ,
...

Useful Results about Determinant of Matrix :
i)
The determinant of only square matrix
exists
...

iii) The determinant of a diagonal matrix is the
iv) The determinant of a triangulate matrix is
v) If A is a square matrix and n  N then
| An | = | A |n
14) Singular Matrix :
A square matrix A is said to be Singular if |A|=
0
...

A square matrix A is said to be Non–Singular if
| A | ≠ 0
...

16) Involutory matrix :
A square matrix A is said to be Involutory
matrix if A2 = I
...

i
...
a11 = b11, a12 = b12
...

Addition & Subtraction of Matrices
If two matrices are of the same order, then only
they can be added or subtracted
...


MHT – CET / JEE (Main)

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

*

Note :
If A is orthogonal matrix then
| A |= ±1 and A–1 =AT
If A and B are two orthogonal matrices, then
AB and BA are both orthogonal matrices
...

i
...
A + B = B + A
ii) Associative law
Addition of matrices is associative
i
...
(A + B) + C = A + ( B + C)
iii) Existence of additive Identity
A+0=0+A=A
Provided that matrices are conformable for
iv) Existence of additive inverse
A + (–A) = A – A = 0
Here (–A) is called as Additive Inverse of
A
...

Then the matrix whose
product
diagonal
elements
...

elements of the matrix A is called the negative
of the matrix A and is denoted by –A
...

Thus if A = [aij]m × n then kA=[kaij]m × n
Properties of scalar multiplication :
Let A=(aij)m × n and B= (bij)m × n be any matrices,
m & n are scalars then
i) (m + n) A = mA + nA …
...

i
...
[A]m × n × [ B ]n × p = [A B]m × p
Laws of Matrix Multiplication :
i) Associative law

[3]

Matrices

i
...
AB ≠ BA
...
If A is the given
matrix then A–1 exists if A is non singular
matrix
i
...
| A | ≠ 0, i
...
A is invertible matrix
...

i)

Elementary Row Transformations :
To find the inverse of given matrix by using this
method use AA–1 = I
...

Note : *(AB)–1 = B–1 A–1
...

A
*  A '  (A 1 )', (A 1 ) 1  A ,
1

iii) Method of adjoint of matrix :
a b c 
If A = d e f  and | A | ≠ 0


g h i 

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

A(BC) = (AB)C
ii) Distributive laws
A(B + C) = AB + AC …left distributive law
(A + B)C = AC + BC… right distributive law
iii) (kA)B = A(kB) = k(AB), k is any scalar
...

v) Multiplication by Zero Matrix
...

vi) Matrix multiplication is not commutative
...
It is denoted by adj
...

a b 
 d b
e
...
If A = 
then Adj
...
A | = 0
...
The determinant
obtained by removing it’s ith row and jth column
in | A | is called as Minor of element aij
...

 3 5 1
If A = 1 2 0  then


 2 3 4 
minor of (–3) =

minor of (–2) =

[4]

3 1
1

0

3 1
2

4

=1

= 14

*

Cofactors :
Let A be the square matrix
...
It
is denoted by cij, Aij
In above example,
∴ Cij = Aij = (–1)i+j ×
mij
Cofactor of –3 = (–1)3+2 × 1
= –1
2+2
Cofactor of –2 = (–1) × 14 = 14

*

Solution of Linear Equations :
We can solve the given linear equations by
using
i) Reduction method ii) Method of inversion
...
A
|A|
–1

MHT – CET / JEE (Main)

*

Some Useful Results :
If AB = AC & | A | ≠ 0 then B = C
AB = 0, does not mean that A = 0 or B = 0
...

(A – B)2 = A2 – AB – BA + B2
...

If A is a square matrix of order n and k is scalar
then | KA | = Kn | A |
If A and B are non singular matrices of same
order then adj(AB) = (adj
...
A)

Matrices

*
*

 

adj A 1   adj
...
A  A

n 1

ii) adj(kA)  k n 1adj(A)
iii) adj
...
A
 n 12

iv) adj
...
A

iv) adj A

n

n

, where n is order of A

, n N

1
1
1
vi) A 1 
 A
 adjA 
A
A
1
1
vii)  adjA  
viii)
A
A
1
 KA 1  A1,  K  0
K
cos   sin 
ix) If A  
 , then
 sin  cos  
cos  n   sin  n 
An  

...

The adjoint of a diagonal matrix is a diagonal
matrix
...

If A is symmetric, then A–1 is symmetric
...

Inverse of symmetric matrix is symmetric
...

All the entries in the inverse of a matrix A are

v) A 1 

*
*
*
*
*
*
*
*

integers if and only if A  1
...

Value of determinant of matrix A is obtained by
sum of product of elements of a row or a
column with corresponding cofactors
...
: a11c 21  a12c22  a13c23  0

A (adj
...
A) A= | A | I, where A is
square matrix and I is identity matrix of order n
...

1 5 3
e
...
If A=  2 3 1 then


 2 6 5
trace of A is 1 – 3 + 5 i
...
3

Note :
i)
ii)
iii)
iv)

Trace(A) = Trace(A’)
Trace(A + B) = Trace A + Trace B
Trace(KA) = K Trace A
...
Trace B

*

Cayley Hamilton Theorem :
Every square matrix satisfies its characteristics
equation
...


*

Homogeneous and Non Homogeneous System
of Linear Equations :
i) Homogeneous System :
If AX = B and B = 0 i
...
AX = 0
e
...
2x + 5y = 0, 3x – 2y = 0 is a
homogeneous system of linear equations
...
g
...


*

Solution of Non Homogeneous System of
Linear Equations :
a) If AX = B, B  0 and A is non singular
i
...
A  0 then system has unique solution
i) Matrix Method
ii) Reduction Method
b) If AX = B, B  0 and A is singular
i
...
A  0 then system may be consistent
with infinitely many solutions or system
may be inconsistent
...

ii) If A  0 , then the system has infinitely
6)

MULTIPLE CHOICE QUESTION
1)

The values of x for which the matrix
2
 x x
2
x  x  will be non-singular are


 x 2  x 

2)

a) 2  x  2

b) For all x other than 2 and -2

c) x  2

d) x  2

1 2 3
In order that the matrix  4 5 6  be non 3  5 
singular ,  should not be equal to

a) 1
3)

If a ij 

b) 2

c) 3

d) 4

1
 3i  2 j and A   a ij  22 , then A 1 is
2

equal to

4)

 1 / 2 2
a) 

 1/ 2 1 

1 / 2 1/ 2 
b) 
1 
 2

2 
 2
c) 

1 / 2 1/ 2 

 2 / 3 1/ 3
d) 

 4 / 3 1 

If A is square matrix for which a ij  i 2  j2 , then
A is
a) Zero

b) Unit

c) Symmetric matrix

d) Skew Symmetric matrix

1 2 2 
5) If A   2 1 2 
 a 2 b 

is a matrix satisfying

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

many solutions
...
Then A100 

1



b) 299 A

c) 298 A

d) A

 1
1  x  
sin  x  tan    
1
 
If A  

  1  x 
1
 sin   cot  x  



 1
1  x  
s in  x  tan    
1
  
B 

  1  x 
1
 sin    tan  x  



Then A – B is equal to
a) I

9)

b) 0

c) 27

d)

1
I
2

If A is a square matrix such that A 2  A ,
then  I  A   A is equal to
3

a) A

10)

b) I – A

c) I

d) 3A

1 2 3   1 2 
 4 5 6 
If P   2 3 4   2 0  
then
0
0 1 

 3 4 5   0 4 

 p 22  
a) 40

b)  40

c)  20

d) 20

AA T  9I3 ,

MHT – CET / JEE (Main)

[6]

Matrices

1 a 2
11) The matrix A  1 2 5  is not invertible if a


 2 1 1 

17)

has the value
a)

2

b) 1

13)


6

b)

b)  5

d)

3
2

c)  1

d) 25

If A and B are square matrices of the same
order such that  A  B  A  B   A 2  B2 , then

 ABA 

1 2

2

a) A B
15)

c) 

Suppose A is a matrix of order 3 and
B  A A 1
...
A  is equal to………
...

a) 1
19)

b) –1

c) 2

d) 3

0 1 
2
If 
 , then adj
...

1
0


 3 2
a) 

 2 3 

 3 2
b) 

 2 3

 3 2 
c) 

 2 3

 3 2 
d) 

 2 3

1 2
k 0
20) If A  
and B  

 and the sum of
3 6
 1 2
all elements of adj
...
 AB  
...

a) 3

MHT – CET / JEE (Main)

b) 16

b) – 3

c) 20

d) – 20

Matrices

x 2  5x  9  0 , then adj
...
 kA   k

n

2



 31


...
A  , then the sum of all

a) 9A

possible values of n is……
b) – 11

c) 11

d) – 1

24) If B is a 3  3 matrix such that B2  0 , then
determinant of adjoint of [  I  B   2B ] is
2

a) 2

b) 0

c) 1

d) – 1

25) If A and B are 3  3 matrices such that A  2
and B  1 , then the determinant of adj
...
A    adj
...
A  A

n 1

c) adj
...
A 

T

d) adj
...
A  adj
...
8 0
...
 A  lies in the
0
...
8 
interval …
...
X)
t 
z
is………

y
 t
a) 

z  x 

z
 t
b) 

 y x 

 t y
c) 

z x 

 t z 
d) 

 y x 

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

a) 1

b) 729 I

c) 9 I

d) 81 I

30) If A is a square matrix of order n, such that
A  3 and adj
...
M   8
...

a) 64

b) 8

c) 2

d) 4

 4 
5 6
32) Let A  
and B  

,
 3 3
 4 3
then for what value of , adj
...
B ?
a) 0

b) –1

c) 1

d) –3

1 4
 5 1
33) Let A  
and B  

 , what value
3 2 
 3 k 
must k have, so that A(adj
...
B) ?
a)

17
5

b) 

17
5

c)

7
5

d) 

7
5

 2 3
34) If A  
, then adj
...


 4 1 
 72 84 
a) 

 63 51 

 51 63
b) 

84 72 

 51 84 
c) 

63 72 

 72 63
d) 

 84 51 

35) The element of second row and third column in
 1 2 1
inverse of the matrix  2 1 0  is ……
 1 0 1 

a) 1

b) –1

c) 2

d) –2

29) If a square matrix A of order 3 is a solution of

MHT – CET / JEE (Main)

[8]

Matrices

36) If both the matrices A and B are non-singular

then the value of x is equal to……
...
b) symmetric matrix

37) If A   a ij 

d) a skew-symmetric

i  j, if i  j
and a ij  
,
2 2
i  j, if i  j

then A 1  …
...
The value of 3AB1 is………
...
 A 2  2A


 2 1



a)

1
25

b) 5

c) –5

d) 48



1

 
...

1 3 , then det
...
 A  
...

a) 5

d) 

c) 25

b)  1

1
5

46) Square matrices L, M, N and P are of same
order and invertible such that L  MN 1P
...

A 1  

3  1 0 
1  1 3 
2 

b)

1  1 3 
2  0 2 

d)  1 
3 1

a)  
21
c)

48) If A 1 

1  1 3 
3  1 2 
1 3 
2 

1  5 3
and A 2  xA  yI  0
...

a) (9, –14)

b) (–1, 14) c) (1, 14) d) (–9, 14)

cos  sin  
 1 0
, B
49) If A  

 and
 sin   cos 
 1 1 
1

is equal to…

cos  sin  
b) 

 sin   cos 

 1 0
a) 

 1 1 

  cos  sin  
d) 

 sin  cos 

1 0 
c) 

1 1 

50) If A is non-singular symmetric matrix, then
1

is…

a) a scalar matrix
...
 denotes the greatest
integer

function,

then

the

det  3P 2 QR 1   is equal to …



a) 2

b) 3

value

c) 0

of

d) 4

52) If  is a cube root of unity and
1 1
1 
A
1 
3
1 2

a) A

1
1
2  , then  A 2  is

 

b) A 3

c) I

d) A 2

1 1 1   x   4
53) If  2 1 3  y    0  , then 2x + y + z
1 1 1   z   2
=……

a) 0

b) 4

c) 2

d) –2

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

C  ABA T , then  A T C1A 

 adj
...

1
60) If A = [1, 2, 3], B=  2 , C=[1, 3, 1] and
 
 3
ABC = [p q r], then p, q, r are
a) 14, 42, 14

b) 42, 14, 42

c) 14, 42, 42

d) 42, 14, 14

61) Consider the system of equations in x, y, z as
x sin 3θ – y + z = 0
x cos 2θ + 4y + 3z = 0
2x + 7y + 7z = 0
If this system has a non–trivial solution, then
for any integer n, values of θ are given


( 1) n 
( 1) n 
a)  n 
b)

n



3 
4 


54) If A is square matrix, A’ its transpose,

MHT – CET / JEE (Main)

[ 10 ]

Matrices


( 1) n 
c)  n 

6 


d)

1/2 1/ 2 
 1/ 2 2 
a) 
b) 


 2 1/ 2 
 1/ 2 1
 1 1/ 2
1/ 2 2 
c) 
d) 


1 
1/ 2
1/ 2 1
65) For equations x + y + 7z = 2, x – y + 5z =1,
9x – 6y – 9z = 1, values of x, z are…
1 1
1 1
a) ,
b) ,
c) 1, 3 d) 1, - 3
2 3
2 6
 2 0 3
66) If A   4 3 1  is expressed as the sum of a


 5 7 2 

symmetric and skew–symmetric matrix, then the
symmetric matrix is
 2 2 4
 2 4 5


a) 2 3 4
b)  0 3 7 




 4 4 2 
 3 1 2 
1 0 0 
d) 0 1 0 


0 0 1 

2 2 
1
67) The inverse of  1 3
0  is


 0 2 1 
3 2 6
a)  2 3 4


 3 4 6 

1 2 6 
b) 1 1 2


 2 2 5 

3 2 6
c) 1 1 2


 2 2 5 

 3 6 2
d) 1 2 1 


 2 5 2

MHT – CET / JEE (Main)

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

0 1 
 2 0 1 
62) If A= 
& B   2 3  then AB is



 1 2 3
1 1
a) singular matrix
b) non – singular
c) |AB| = 4
d) scalar
...

b) 3, 3, –11
c) 3, –3, 11
d) 3, 3, 11
5
74) If for matrix A, A = I, then A–1 =
a) A
b) A2
c) A3
d) A4

[ 11 ]

Matrices

85)

 4 2
75) If A= 
 then  A  2I   A  3I  =
 1 1 
a) I
b) 2I
c) 0
d) 3I
76) If A & B are any two matrices such that AB = B

and BA = A then A 2  B2 

 

n n

elements aij = 0, where
a) i < j
b) i > j
c) i = j
d) i ≥ j
79) If A is [A]3×4 matrix and B is a matrix such that
A' B and BA' both are defined then B is of
type
a) 4 × 3 b) 3 × 4
c) 3 × 3
d) 4 × 4
1 1 0
80) A   1 2 1 , which of the following is


 2 1 0 
correct
a) A3  3A2  I  0
b) A3  2A 2  I  0
c) A3  3A2  I  0

d) A3  A 2  I  0

x
81) If A  
1
a) 1
1
82) If A  
3

1
and A = A–1
...

b)     n,n  0, 1, 2,
...

2
n
, n  0, 1, 2,
...

a) A collection of real numbers
b) An array of real numbers
c) An array of real or complex nos
...

78) In a lower triangular matrix, A= a ij
, the

If  is the complex cube root of unity, then
0
 0

2
inverse of 0 
0  is


 0 0  3 
  0 0 
a)  0  0 


 0 0  2 

  2 0 0


b)  0  0
 0 0 1



  3 0 0
 0 0 


c)  0  0
d)  1 0 0 


2
 0 0 1

0
0





86) If A and B are symmetric matrices of order n,
then
a) A+B is skew symmetric
b) A+B is
symmetric
c) A + B is diagonal
d) A+B is zero
matrix
87) If A and B are skew symmetric matrix of order
n then A + B is
...
matrix


  g  h 0 
a) diagonal
b) upper triangular
c) symmetric
d) skew–symmetric
90) If A is a square matrix of order n, then |Adj A| =
a) A

n 2

 

91) If A  a ij

b) |A|n–1
2 2

c) |A|

d) |A–1|

, where aij = i + j then A=
...
A =
a) –1
b) 0
c) 1
d) none
103) For 2 × 2 matrices A, B & I, if A + B = I and
2A – 2B = I, then A =

MHT – CET / JEE (Main)

3/4 0 
a) 

3/4 0 
3/4 0 
c) 

 0 3/4

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

93) If A and B are square matrices of same order
then (A+B)2 = A2 + 2AB + B2 if
a) AB = –BA b) AB = BA c) A2=A d) B2 = B
94) If A and B are two square matrices of same
order three then
a) (AB)' =A' B'
b) AB=0 ⇒A = 0 or B = 0
c) AB = 0 ⇒|A| = 0 and |B| = 0
d) AB = 0 ⇒ |A| = 0 or |B| = 0
 1 1 1 
95) A   0 2 3 , B = (adj A) and C= 5A then


 2 1 0 

1 0
104) If A   0 1

 0 0
a) 3Ab) –3A
0 1
105) If A  0 0

1 1

 0 3/4
b) 

3/4 0 
0 
3/4
d) 

 0 3/4

0
0 , then A2 + 2A =

1 

c) 2A

d) –2A

0
1 then A3 + A =

0

a) 2

b) 3I3
c) I3
d) I2
 i 0
106) If A  
, n ϵ N, i  1 then A4n =

0 i 
a) –I
b) 2I
c) 4I
d) I
107) If A and B are 2 square matrices such that
B = –A–1 BA then (A+B)2 =
a) A2 – B2 b) A2 + B2 c) 2A – 2B
d) A + B
108) The sum of products of elements of any row of a
det
...
A then the expression
a11  c11  a12  c12  a13  c13  a14  c14 
a) 0
b) –1
c) 1
d) |A|
110) Choose correct statement
...

d) a square matrix whose each element is 1 is
an identity matrix
...
(d1, d2, d3)
b) diag
...
d1n ,d 2n , d 3n



d) none

112) For a square matrix A it is given that AA’ = I,
then A is
a) diagonal matrix
b) orthogonal matrix
c) symmetric matrix
d) none
 2 0 1
113) If A =  3 1 2  then adj(A) is


 1 1 2 

[ 13 ]

Matrices

 0 1 1 
a)  8 3 7 


 4 2 2

then f   
...
G  

b) f   
...
G  
d) G   
...
A(ϕ) =

  sin  cos  
a) 81
b) –81
c) 27 d) –27
a) A(θ – ϕ) b)A(θϕ) c) A(θ/ϕ) d) A(θ + ϕ)
120) Let A be an invertible matrix then which of
following is not true?
a) (AB)’ = B’A’
b) (A2)–1 = (A–1)2
c) (At)–1 = (A–1)t
d) A–1 = |A|–1
cos   sin  0
121) If f      sin  cos  0 , then f   
...
matrix
a) skew symmetric b) symmetric
c) orthogonal
d) none
133) If A and B are symmetric matrices of same
order then AB – BA is
...

a) 7K2
b) 7K
c) 73 K d) 7 K3

[ 14 ]

Matrices

3 5 7
A   4 2 1 
 0 3 8 

135) If

then trace (3A) =
...


sin

cos




  cos3  sin 3
cos3 

a) 
  sin 3
 cos3

sin 3 

c) 

  sin 3 cos3

  cos 3 sin 3 

b) 

  sin 3 cos 3
  cos3

d) 
 sin 3

sin3 
 cos3

x
3
1 1 2




157) Let X = y , D = 5 and A =  2 1 1  ,
 
 


 z 
11
 4 1 2
if X = A–1 D, then X is equal to :
 8/ 3 
 8 / 3
8 / 3 
1






a) 0
b)  1/ 3 c)  1 
d) 1/ 3 
 
 0 
 0 
 1 
 2
1 2 3
158) If A = 1 3 4 , then |A–1| is :


3 4 3
a) 1/4
b) 4
c) –1/4
d) –4
 0 3
–1
159) If A = 
 and A = λ(adj
...
adj
...
matrix
 2 

Matrices

a) diagonal
c) singular
168)

If

b) skew–symmetric
d) non –singular
1 0 2
 1 1 2 and adj
...
 P n  0
(0 denotes the null matrix) then P–1 is :
a) Pn
b) – Pn c) –(1 + P +
...
|adj A|

0 3

is equal to :
a) (3)3
b) (3)6
c) (3)9
d) (3)12
 3 3 4
180) If A   2 3 4 then A–1 equals to


 0 1 1
a) A2
b) A4
c) A
d) A3
181) Let A be any 3 × 3 invertible matrix
...
 adj A  

1

b) adj (adj(A)) = A
...

1 1
1 1
D A 
 0 Also, D x  D y 
0
3 3
3 3

c) adj(A)  A
...
A
then,

for all i and j, the co - factor Cij of aij is such that
a) Cij = aji b) Cij = –aji c) Cij = aij d) Cij =(
aij)2
 4 1
183) If A  
 ,then the determinant of the
3 1





matrix A 2016  2A 2015  A 2014 is
a) 2014
b) –175
c) 2016
d) –25
184) Which one of the following statements is true
a) Non- singular square matrix does not have a
unique inverse
b) Determinant of a non-singular matrix is zero
c) If A' = A , then A is a square matrix
d) If, A ≠ 0 then |A
...
g
...
e
...

a1x  b1 y  c1z  d1 ,

a 2 x  b2 y  c2 z  d 2 ,
a 3 x  b3 y  c3z  d3 , d1 or d2 or d3  0
is non homogeneous system in three
unknowns
...


MHT – CET / JEE (Main)

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

 1/ 3 2 / 3 2 / 3
182) If A   2 / 3 1/ 3 2 / 3  a ij  ,


33
 2 / 3 2 / 3 1/ 3 

1 1
 0 i
...
A  0
2 3

iii) No Solution :
Consider equations
x + y = 1,
3x + 3y = 4
Here we cannot find values of x and y
satisfying these equations
 there is no solution
...

This system is of the form AX = B, B  0
This system has
a1 b1 c1
i) Unique solution if D  A  a 2 b 2 c 2  0
a 3 b3 c 3
ii) Infinite Solutions if
a1

b1

D  A  a2

b2

a3

b3

a1
Dy  a 2
a3

d1
d2
d3

c1

d1

b1

c1

c 2  0 , D x  d 2 b 2 c2  0,
c3
d 3 b 3 c3

c1
a1
c2  0, D z  a 2
c3
a3

b1
b2
b3

d1
d2  0
d3

ii) No Solution if
a1

b1

c1

D  A  a2

b2

c 2  0 and

a3

b3

c3

Matrices

b1

c1

Dx  d2

b2

c2  0

d3

b3

c3

a 2 x  b 2 y  c 2 z  0,

or

a 3 x  b 3 y  c3 z  0

a1

d1

c1

a1

b1

d1

Dy  a 2

d2

c 2  0 or D z  a 2

b2

d2  0

a3

d3

c3

b3

d3

a3

Homogeneous System of Linear Equations :
If AX = B and B = 0 i
...
AX = 0
e
...
2x + 5y = 0, 3x – 2y = 0 is a
homogeneous system of linear equations
i
...
constant terms are zero
...

Types of Solutions :
i) Unique Solution :
Consider equations
x + y = 0,
2x + 3y = 0
Here x = 0 and y = 0 is the unique solution
...
e
...

 there are infinite solutions
...
e
...


*

Trivial Solution or Zero Solution :
If values of all unknowns i
...
x, y, z in the
system are zero then system has trivial or zero
solution
...
e
...


*

Solution of a Homogeneous System of
Linear Equations :
Consider the system
a1x  b1 y  c1z  0,

MHT – CET / JEE (Main)

Here, d1  d 2  d3  0
This system is of the form AX = 0,
This system has

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

*

d1

[ 19 ]

i)

Unique or Trivial or Zero solution if

a1
A  a2

b1
b2

c1
c2  0

a3

b3

c3

ii) Infinite or Non Trivial or Non Zero solution if
a1 b1 c1
A  a 2 b2 c2  0
a 3 b3 c3

Note :
i) Consistent equations may have unique or
infinitely many solutions
...

The value of  , such that the following system
of equations has no solution, if 2x – y – 2z = 2,
x + 2y + z = – 4 and x  y  z  4

Matrices

a) 3
b) 1
c) 0 (Zero)
7) If the system of linear equations
x1  2x 2  3x 3  6 , x1  3x 2  5x 3  9

d) – 3

c) a  R  8 and b  R  15
d) a = 8, b = 15
8) The set of all value of  , for which the system
of linear equations 2x1  2x 2  x 3  x1 ,

2x1  3x 2  2x 3  x 2 ,  x1  2x 2  x 3 has a
non - trivial solution ,
a) Is an empty set
b) Is a singleton
c) Contains two elements
d) Contains more than two elements
9) The system of linear equations x  y  z  0 ,

x  y  z  0 , x  y  z  0 has a non trivial

5x  y  3z  y , 3x  5y  z  z has infinite
number of solutions is
a) 1
b) 2
c) 3
13) If the
system
of
linear
x  2ay  az  0 , x  3by  bz  0,

d) 6
equations

x  4cy  cz  0 has a non zero
solution, then a, b, c
a) are in A
...

b) are in G
...

c) are in H
...

d) satisfy a + 2b + 3c = 0
14) The system of linear equations x  y  z  6 ,

is

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

number of solutions, then
a) a = 8, b can be any real number
...

b) Exactly two values of 
...

d) Infinitely many values of 
...
Let us denote by
a1
  a, b, c  the determinant a 2

b1
b2

c1
c2

a3

b3

c3

if   a, b, c   0 , then the value of x in the
unique
a)

  bcd 
  abc 

solution of the above equations is

  abd 
 acd
b)   bcd  c)   d)
  abc 

  abc 

  abc 

18) Consider the system of linear equations
x1  2x 2  x 3  3, 2x1  3x 2  x 3  3,

3x1  5x 2  2x 3  1
...
Suppose
that there are real numbers x, y, z not all zero
such that x = cy + bz, y = az + cx, z = bx + ay
have a
solution, then a 2  b 2  c2  2abc 
a) – 1
b) 0
c) 1
d) 2
21) The number of solution of the equations
x 2  x 3  1,  x1  2x 3  2, x1  2x 2  3 is
a) Zero

b) One

c) Two

d) Infinite

x  2y  3z  10 and x + 2y + az = b has no
solution when

MHT – CET / JEE (Main)

[ 20 ]

Matrices

Multiple Choice Questions From
MHT CET

a) A + B = B + A and A + (B + C) = (A + B) + C
b) A + B = B + A and AC = BC
c) A + B = B +A and AB = BC
d) AC = BC and A = BC
 2 4
3) A  
Then A2 =

 1 2
0
b) 
 4
0
d) 
0

a) Null matrix
c) Unit matrix

16 
0 
0
1

 a h g
x


4) A = [x y z], B   h b f  , C   y 
 g f c 
 z 
then ABC =
a) ax  by  cz  2gx  2fy  2cz 
2

2

2

b) ax  by  cz  2hxy  2by  2cz 
2

2

2

c) ax 2  cy 2  bz 2  xy  yz  zx 
d) ax 2  by 2  cz 2  2hxy  2gxz  2fyz 

3 3
0
x
5) A   3 0 4 , B   y  Then B’(AB) is
 3 4 0 
 z 
a) Null matrix
b) Unit
c) Singular
d) Symmetric
MHT CET – 2005MHT CET – 2005
 1 2
1 3 2 
1) If A   3 2 , B  
then AB =
4 1 3

 1 0 

 9 1 4 
a)  11 7 0 
 1 3 2

1 4
 9

b)  11 7 0 
 1 3 2

 9 1 4 
c) 11 7
0 
 1 3 2 

MHT – CET / JEE (Main)

 9 1 4
d) 11 7 0
 1 3 2

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

MHT CET – 2004
1 2 
2
1) If A  
 Then A – 5A is equal to
3
4


a) 2I
b) 3I
c) –2I d) Null matrix
 2 1
 1 2 
 1 3
2) A  
,B
, C 


 then
 1 2 
2 1 
2 1 

2)

3)

4)

 3 2
AI 
 then ( A + I ) (A – I ) =
4 1 
 5
a) 
8
1
A
2

4 
 5 4  5 4 
5 4 
b)
c)
d)
 8 9 8 9
8 9 
9

 




1
1 a 
, If (A + B)2 = A2 +
,B  


1
4 b
2
B then a and b are
a) 1, –1
b) 1, –2 c) –1, 1
d) 0, 2
 2 1 1 
If A   2 3 2 then A2 =
 4 4 3

a) null matrix
b) it self A
c) unit matrix
d) scalar
MHT CET – 2006MHT CET – 2006
1 0
1 0
1) If A  
, B

1 0 , then AB =
0 1
a) a null matrix
b) an identity matrix
c) matrix A
d) matrix B

2)

3)

4)

1)

2)

3)

 cos  sin  
If A( )  
, then A 2 ( ) =


sin

cos



a) 1
b) 2
c) 3
d) 0
 8 4
 5 4 
2
, B
If A  

 , then (A + B) =
10
5
10

8





a) A2 + B2
b) A2 + BA+ B2
c) A2 + AB + B2
d) A2 + 2AB + B2
If A is square matrix of order n, then |KA| =
|A|
a) K | A | b) K n A c) n d) None of
K
these
MHT CET – 2007MHT CET – 2007
 2 2
1 1
If A  
, B
1 1 , then
2 2 
a) A–1 = B

b) B–1 does not exists

c) A–1 does not exists

d) both b & c

5 4 
If A  
then A–1 =

3 2 

a)

1  2 4 
2  3 5 

b)

c)

1  5 4 
2  3 2 

1  2 4 
d)  
2  3 5 

1  5 3
2  4 2

Matrix A is of order m x n , matrix B is of order
p x q such that AB exists, then

[ 21 ]

Matrices

a) m = n
4)

c) m = q

1
The matrix A satisfying A 
0
3 2 
3
a) 
b) 

 6 3
6

d) p = q

5  3 1
is

1  6 0 
16 
30 

 3 16 
 3 3
c) 
d) 


 6 30 
6 2 
MHT CET – 2008MHT CET – 2008
 4 1
2
A
 and A  6A  7I  0 , then K =

1
K



a) –2

2)

1)

2)

b) 10
c) –10
d) 2
 3 2 6
 1 2 2


A  1 1 2 , B   1 3 0  are
 2 2 5
 0 2 1 
a) inverse of each other
b) transpose of each other
c) negative of each other
d) equal
MHT CET – 2009MHT CET – 2009
 3 2 4
If A  1 2 1 and Aij are the co factors of aij


3 2 6
then, a11A11 + a12A12 + a13A13 =
a) 8
b) 6
c) 4
d) 0
 cos   sin  
If A  
 and AB = BA= I then B
 sin  cos  
=
  cos 
a) 
 sin 
  sin 
c) 
 cos 

1)

sin  
cos 

 cos  sin  
b) 

  sin  cos  
cos  
 sin   cos  
d) 


sin  
  cos  sin  
MHT CET – 2010MHT CET – 2010
 cos   sin  
Let A  
 then the inverse of A
  sin   cos  

is
 cos   sin  
a) 

  sin   cos  
 sin   cos  
c) 

cos   sin  

2)

  cos  sin  
b) 

 sin  cos 
  sin   cos  
d) 

  cos  sin  

a b
1
If A  
 then A is equal to
c
d



MHT – CET / JEE (Main)

1  d b
ad  bc   c a 
c) ad – bc
d) – ad + bc
MHT CET – 2011MHT CET – 2011
 cos  sin  
If A  
 and AB = BA = I, then
  sin  cos  
the matrix B is
 cos  sin  
 cos   sin  
a) 
b) 


  sin  cos  
 sin  cos  

a)

1)

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

1)

b) p = n

1
ad  bc

cos   sin  
c) 

 sin   cos  

2)

b)

  cos  sin  
d) 

 sin  cos 

7 6 1  4 2 3 
If A  4 2 3   1 3 0  then A =

 

1 3 0  7 6 1
1 0 0
a) 0 1 0


0 0 1 

1 1 0
b) 0 0 1 


0 1 0

0 1 0
0 0 1


c) 0 0 1
d) 0 1 0




1 0 0
1 0 0
MT CET – 2013T CET – 2013
 cos  sin  0
1) If A    sin  cos  0 , where A11 ,A12 ,A13


 0
0
1
are cofactors of a11 ,a12 ,a13 respectively, then the
value of a11A11 ,a12A12 ,a13A13 is

2)

1)

a) –1
b) 1
c) 0
d) 1/2
1 3 3  x  12
If 1 4 4  y   15 , then the values of x, y,

   
1 3 4  z  13
z respectively are
a) 1, 2, 3 b) 3, 2, 1
c) 2, 2, 1
d) 1, 1, 2
MHT CET – 2016MHT CET – 2016
1 1 0

If A   2 1 5 , then a11A21  a12A 22  a13A 23 


1 2 1 

a) 1
2)

[ 22 ]

b) 0

c) –1

d) 2

 2 2
 0 1
–1 –1 –1
A
,B  

 then (B A ) =

3
2
1
0




2 2 
 2 2
 2 3
 1 1
a) 
 b)  2 3  c)  2 2  d)  2 3 
2
3









Matrices

3)

MHT MHT CET – 2019 ( Online ) 2019 (Online)

1 2
If A  
 such that AX = I, then X =
 4 3
1 1 3 
1 4 2 
b)
5  2 1
5  4 1
1  3 2 
1  1 2 
c) 
d) 

5  4 1
5  1 4 
MHT CET – 2017MHT CET – 2017
1 0 0 
The inverse of the matrix 3 3 0  is


5 2 1

1)

1
 4 3 2
and
A   1


 1 2 0 

If A  

 1

a)

2)

3)

 3 0 0 
1
a) 
3 1 0


3
 9 2 3

 3 0 0
1
b) 
3 1 0 


3
 9 2 3

 3 0 0
1
c) 
3 1 0 


3
 9 2 3

 3 0 0
1
d)  3 1 0

3
 9 2 3

 14 1
If the inverse of the matrix  2 3 1  does


 6 2 3 
not exist then the value of α is
a) 1
b) –1
c) 0
d) –2
10 0 
For a invertible matrix A if A  adjA   

 0 10
then A 
...
B 
...
A  then k


k
0 1 1 
=
1) 7
2) 11
3) –11
4) –7
1 2 x 
If the inverse of matrix A   4 1 7  does


 2 4 6

not exist, then x =
...
A   
 then | A | =
 0 10
1) 0
1)

2)

[ 23 ]

2) 10
3) 100
4) 20
MHT CET – 20202020 ( Online )
 2 3
1 0 
–1
If A  
,B  

 , then (AB) =
1
2
3
1




 2 3
 2 3
1) 
2) 


 7 11 
 7 11 
 2 3 
 2 3
3) 
4) 


 7 11
 7 11 
 cos   sin  
–1
If A  
 , then A =

sin


cos



  sin   cos  
1) 

  cos  sin  

 sin   cos  
2) 

cos   sin  

Matrices

  cos  sin  
3) 

 sin  cos 

3)

5)

6)

 2 1
If A  
, such that A2  4A  3I  0,

 1 2 
then A–1 =
1 2 1
1  2 1
1) 
2)

3 1 2
3  1 2 
1  2 1
1  2 1 
3) 
4)

3  1 2 
3  1 2

Which of the following matrix is invertible ?
 1 2 3 
 4 2


A1  
 , A2   4 5 7  ,
2
1


 2 4 6

 1 0 0
1 0 1


A3  5 2 1 , A 4   0 2 3




7 2 1
1 2 1
1) A4
2) A3
3) A2
4) A1
2 0 0 
If A   0 2 0  , then A4 A–1 =


 0 0 1
8 0 0 
1) 0 8 0 


0 0 1

8 0 0
2) 0 8 0


0 0 1 

0
0
1/ 2
3)  0 1/ 2 0 


 0
0
1

 4 0 0 
4)  0 4 0 


 0 0 1

 2 3
The adjoint of the matrix A  
 is
3 5 
 5 3
5 3
1) 
2)

3 2 
 3 2



3)

7)

1  5 3
19  3 2

4)

1 5 3
19  3 2 

 2 3
 2 3
If A  
and B  

,
1 2
 1 2 
–1

–1 –1

then (B A ) =
0 1
2 3 
1 2
1 0 
1) 
2) 
3) 
4) 




1 0 
 1 2 
 3 4
0 1

8)

1 2 1 
1
If A  1 1 1  , then adj adjA   


1 1 0

MHT – CET / JEE (Main)

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

4)

1) A–1

 cos   sin  
4) 

  sin   cos  

2) I

3) A2

4) 2A

 x 2 3
9) The value of x such that the matrix  4 5 6


 2 3 5
is not invertible is
10
7
7
10
1)
2)
3)
4)
7
10
10
7
 0 0 1
10) If A   0 1 0  , then


 1 0 0 
1) A–1 = I
2) A is not invertible
–1
3) A = 2A
4) A = A–1
1 0 2 
11) If A   2 1 3  , where Aij is the cofactor of


 0 3 5
the element aij of matrix A, then
a 21A 21  a 22 A 22  a 23A23 
1) 0
2) 26
3) –26
4) –2
12) If the elements of matrix A are the reciprocals of

 1  2 


elements of matrix    2 1  , where  is
 2 1  


complex cube root of unity, then
1) A–1 = A2
2) A–1 = A
3) A–1 = I
4) A–1 does not exists
1 2
1 2 1
13) If A  
, B   2 1 , then (AB)–1 is



 2 1 0
 0 1 
 1   5 5
1)   
 5   4 5 
 1   5  5
3)   
 5   4 5
 1 0
1
14) If A  
,I  

 1 7 
0

then the value of k is
1
1)
2) –7
7

 1   5  5
2)   
 5   4 5 
 1   5  5
4)   
 5   4 5
0
and A2 = 8A + kI,
1 

3)

1
7

4) 7

1 1 1 
1


15) If AX = B, where A  2 1 0 , B   1 ,


 
 3 3 4
 2

[ 24 ]

x
and X   y  , then x + y + z =
 
 z 

Matrices

1) 1
1
16) If A  
1
1 3
1)
7  4

2) 3

3) 6

4) 2

3) –A
1 3
24) AX = B, where A  1 4

1 3

1
 4 1
–1
,B  

 , then (A + B) =
2
3
1


2
5 

 3 2
2) 7 

4 5
1  3 2 
4) 
7  4 5 

 a 1 4
17) The matrix A   3 0 1  is not invertible


 1 1 2 

only if a =
1) –17
2
18) If A  
1

2) –16
3) 16
4) 17
3
1 0 
, then B–1 A–1 =
,B  


2
3 1 
 2 3
2 3 
1) 
2) 


 7 11 
 7 11

 2 3
 2 3 
3) 
4) 


 7 11 
 7 11
19) The sum of the cofactors of the elements of
 1 3 2
second row of the matrix  2 0 1  is


 5 2 1

b) 3

3) 5

4) –23
 3 1 1
 2 0 1
1


20) If A  5 1 0
and A   6 5 ,




  2 2 
 0 1 3 
then the values of  and  are respectively
...

1 2
1 2
1 2
1 2
,
,
,
,
1)
2)
3)
4)
11 11
11 11
11 11
11 11
MHT CET – 2021MHT CET - 202
 2 2
 0 1
1) If A  
,
B


1 0  ,
 3 2


–1 –1 –1
then (B A ) =
...

a) –1000 b) 100
c) 20
d) –10
1 2 3 
13 2 b 


If A   1 1   and B   3 1 2 
 2 4 7 
 2 0 1 
where matrix B is inverse of matrix A, then the
values of a and b are
...
A =


 0
0
1 

cos   sin  0
a)  sin  cos  0


0
1
 0

cos  sin  0
b)  sin  cos  0


0
1
 0

  cos   sin  0
 cos  sin  0


c) sin 
cos  0 d)   sin  cos  0




 0
 0
0
1 
0
1
5)

6)

7)

 0 1 2
If A  1 2 3 , then A–1 =
...

1 1
1
a) ,
b) –1, 1 c) 2, 
d) 1, –1
2 2
2
1 0 2
 5 x 2 


If A  1 1 2 , adj
...

a) 3
b) 6
c) 4

MHT – CET / JEE (Main)

d) 5

GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

3)

For a 3 × 3 matrix A,
0 
 10 0

if A  adj
...

If A 1   
2  1 2 
where I2 is a unit matrix of order 2
...
A) = 
 , then | A | =
...
A) = AA , then
3
2


5a + b = ?
a) 5
b) 13
c) –1
d) 4
 1 2
 1 2 1


12) If A  
 and B   3 1  then

1
1
3


 0 2
(AB)–1 =
...

1
1
a)
b) –6
c) 36
d) 
36
6
2
k
–1
14) If A  
 , then A does not exist if k =

2

k



...
Thrice the third
number when added to the first number gives 7
...
The product
of these numbers is
...

a) 4
b) 6
c) 5
d) 3
 1 2 3
18) If A   1 1 2 , then A(adj
...



 1 2 4

 1 1 1 
a)  2 1 2


 3 2 4

 3 0 0
b) 0 3 0


0 0 3

 1 2 3
c)  1 1 2


 1 2 4

d)

0
0 
 1/ 3
 0
1/ 3
0 


 0
0
1/ 3
 1 2 3
19) If A   1 1 2  and A(adj
...

a) 625
b) 256
c) 81
d) 16
 i 
1
20) If A  
 and A does not exist, then
i




λ =
...



 1 3 4
a) 13, –6, –5
b) –13, 6, 5
c) –13, –6, 5
d) 13, 5, 6
 3 2 6
1
22) If A   1 1 2 , then A =
...

5

2


1
1
a) 19
b) –19
c)
d) 
19
19
 x1 
 1 1 1 
1 




17) If A  2 1 0 , B  1 and X   x 2 


 
 x 3 
 3 3 4
 2

 5 20 2
a)  1 3 0


 3 11 1 

 5 20 2 
b)  1 3 0 
 3 11 1 

 5 20 2 
c)  1 3
0

 3 11 1 

 5 20 2 
d)  1 3 0 


 3 11 1

 2  3
 1 0
23) If A 1  
and B 1  

 , then
 1 2 
 3 1 

 AB

1



 2 3
a) 

 7 11 

2 7 
b) 

 3 1

2 3 
c) 

 7 11

 2 7 
d) 

 3 11 

MHT CET – 2022MHT CET - 202

1 3
1) If A  a ij    1 2
33

 1 1
of aij then a 31 A 31  a 32 A 32
a) 0

b) 20

3
2 and Aij is a cofactor

4
 a 33 A 33 is equal to

c) 5

d) 15

 2 3
2) If A  
 , then A + adj A is
4 1 
 1 3
 3 0
1 0
1 3
a) 
b)
c)
d)

 0 3
0 1
4 2 
 4 2







 3 2 4
3) If A  a ij   1 4 1 and Aij is a cofactor of
33


 2 6 3
aij, then the value of a 21A 21  a 22A 22  a 23A 23 is
equal to
a) 18

b) 8

c) –8

d) 0

 2 3
4) If A  
, then adj (3A2 +12A) is equal to

 4 1 

[ 27 ]

 21 63
a) 

 84 0 

 21 63
b) 

84 0 

 21 63
c) 
0 
 84

 21 63
d) 

84 0 

Matrices

5) The element in the third row and second column
 3 2 6
of the inverse of the matrix 1 1 2 is


 2 2 5
b) 1

c) –2

d) 2

 1 2 3
6) If A  a ij  1 1 5 and Aij is a cofactor of
33 

 2 4 7 
aij, then a11A 21  a12 A 22  a13 A 23 is equal to
a) 1

b) 0

c) 2

d) –1

 1 3 2
7) If A   3 0 5 and A(adj A) = KI, then the


 2 5 0 
value of K is, (where I is unit matrix of order 3)
a) –85

b) 85

c) –25

d) 25

1  2i i  2
 0

8) If A  1  2i
0
K  and A 1 does not


 2  i
7
0 
exists, then K =…
...

 3 / 2 1/ 2 
1 1
If P  
, A  
 and
3 / 2
0 1
 1/ 2
Q = PAPT then PTQ2005P is
 1

1 2005
1 

2)

[ I
...
T
...
I
...
E
...
– 2003]
a)   2ab,   a 2  b2
b)   a 2  b2 ,   ab
c)   a 2  b2 ,   2ab
d)   a 2  b 2 ,   a 2  b2
3)

 0
1 0 
If A  
, A 2  B then value
,B  


 1 1
5 1 

of  is
a) 4
4)

b) –1

[ I
...
T
...
I
...
E
...
– 2011]
a) 0
5)

[ 28 ]

b) –H

c) H2

d) H

1 0 0
Let A   2 1 0
...
I
...
E
...
– 2012 ]
a) –2
b) 1
c) 0
d) –1
Let P  a ij  be a 3 × 3 matrix and let
Q   bij  , where bij  2i j a ij for 1  i, j  3
...
I
...


2012 ]
a) 210
8)

b) 211

c) 212

d) 213

If P is 3×3 matrix such that PT = 2P + I, where
PT is the transpose of P and I is the 3×3 identity
matrix, then there exists a column matrix

 x  0
X   y   0 such that :
 z  0

[ I
...
T
...
I
...
– 2012 ]
a) 4
b) –1
c) 1
d) +2
 5 5  
10) If A   0  5  , | A2 | = 25, then | α |=


 0 0
5 

1
a) 
5

[ A
...
E
...
E
...
I
...
E
...
– 2012]

 1 1 1 
 4 2 2


11) If A  2 1 3 , 10 B   5 0 k  , B




1 1 1 
 1 2 3 
is inverse of A then k =
[A
...
E
...
E
...
I
...
E
...
– 2004 ]
a) A is a zero matrix
b) A = (–1) = I, where I is a unit matrix
c) A 1 does not exists
...
I
...
E
...
– 2005 ]
a) A
b) A + I
c) I – A
d) A – I
1 0
1 0
14) If A  
,
I


 0 1  , then which of the
1 1 


following holds for all n ≥ 1, by the principle of
mathematical induction
...
I
...
E
...
– 2005 ]
a) A  2n1 A   n  1 I

b) A  nA   n  1 I

c) A  2n1 A   n  1 I

d) A  nA   n  1 I

n

n

n

n

1 0 0
1
15) A  0 1 1  and also A 1  A 2  cA  dI


6
0 2 4





, where I is a unit matrix, then the ordered pair
(c, d ) is
a) (–6,11 )

[I
...
T
...
I
...
E
...
–2006]
a) A = B
b) AB = BA
c) either A or B is a zero matrix
...

1 2 
a 0
17) Let A  
and B  

 , a, b ϵ N then
3 4
0 b

[ 29 ]

Matrices

a) If det A  1, then A 1 need not exist
...

c) If det A  1, then A1 exists and all its
entries are non–integers
...

19) The number of 3×3 non singular matrices, with
four entries as 1 and all other entries as 0 is
[ A
...
E
...
E
...
I
...
– 2010 ]
c) 168
d) 2

JEE Main 2019
cos   sin 
, then the matrix A 50 When
1) A  

 sin  cos  



is equal to
12
 1
3



2 
1)  2
 3
1 


 2
2 

 3

2)  2
 1

 2



3) 




 1

4)  2
 3

 2

3
2
1
2

1
 
2
3

2 

MHT – CET / JEE (Main)

1 

2 
3

2 
3

2 
1 

2 

2)

If
e t

A  e t
e t


GHONSE MATHS ACADEMY – MHT CET – GHONSE MATHS ACADEMY – MHT CET

[ A
...
E
...
E
...

c) there exists exactly one B such that AB = BA
...
Then which of the following is true?
[ A
...
E
...
E
...
Then

equal to
1) 135
2) 9
3) 10
4) 15
6) If
1 1 1 2  1 3
1 n  1  1 78
,

 0 1  0 1   0 1
...
Then, the value of α is
A 32  
 1 0 


32

b) 0

c)


64

d)


16

10) The total number of matrices
 0 2y 1 
A   2x y 1 ,  x, y,  R, x  y  for which


 2x  y 1 
A T A  3I3 is

a) 2

b) 4

c) 3

d) 6

JEE Main 2020
1)

Let  be a root of equation x 2  x  1  0 and

1 1
1 
matrix A 
1 
3
1  2

1
 2  , then the matrix

 4 

31

2)

A is equal to
1) A3
2) A2
3) I3
4) A
Let A = [aij] and B = [bij] be two 3 × 3 real
matrix
such that bij   3

 i j2

a ji ,

where i, j = 1, 2, 3
...
If the matrix A   b c a 


 c a b
satisfies ATA = I, then a value of abc can be
a) 

6)

1
3

b)

1
3

c) 3

d)

2
3

 x 1
Let A  
, x  R and A 4 = [aij]
...

a) 10
7)

a ji

MHT – CET / JEE (Main)

31 a12
31 a 22

a11
2 1
81  3  3 3 a 21

[ 31 ]

b) 20

c) 15

d) 25

 cos  isin   

If A  
,     and

24 
i sin  cos   
a b 
A5  
 , where i  1 , then which one of
c d

the following is not true?
a) a2 – d2 = 0
c) a 2  b 2 

1
2

b) a2 – c2 = 1
d) 0  a 2  b 2  1

Matrices

JEE Main 2021
0 2
1) If the matrix A  
satisfies ,
 K 1

1 0 0
equation A  A  A  0 4 0 for some


0 0 1
real numbers α and β, then β – α is equal to
...
Then A2025 – A2020 is equal to


 1 0 0

a) A6 – A b) A5

c) A5 – A

d) A6

 1 0
50
3) If P  
 , then P is
1
/
2
1


 1 0
1 50
a) 
b) 


 25 1
0 1 

1 25
 1 0
c) 
d) 


0 1 
50 1

 1 2 0
 2 1 5 


4) Let A  2B  6 3 3 and 2A  B   2 1 6
...
Then the value of n ∈N for which
 5 3
Pn = 5I – 8P is equal to
...
Then the system of
 i i 
linear equations A8  x    8  has
 y  64 

a) a unique solution

b) infinitely many solutions

c) no solution

d) exactly two solutions
Title: Matrices
Description: Matrices 12th CET notes